1. Field of the Invention
The present invention relates to an angle detection apparatus, a motor driving control apparatus including the angle detection apparatus and an angle detection method.
2. Description of the Related Art
When controlling the rotation angle of a motor (i.e., position control), it is necessary to detect the rotation angle of the motor. As a common way, there is a method of detecting the rotation angle of the rotor by connecting a rotary encoder to the rotation shaft of the rotor of the motor. In this method, two-phase pulse signals having the phase difference of a quarter cycle and changing according to the rotation angle are output, and a relative rotation angle is detected by detecting the edges of the signals and the High (Hi)/Low (Lo) states of the two phases.
For example, an optical encoder uses a disk having slits placed circularly at equal intervals near a peripheral edge part and two photo interrupters placed having a distance that is ¼ the pitch of the slits of the disk. By binarizing the output signals of the two photo interrupters, it is possible to obtain the above-mentioned two-phase pulse signals.
As a method of detecting the rotation angle of a rotating member, the following method is also known. In this method, a rotating member having a permanent magnet mounted thereon and a magnetic sensor installed near the rotating member are rotated relatively. The rotation angle is detected from the output waveform of the magnetic sensor changing according to the rotation, and the above-mentioned two-phase pulse signals are output according to the thus detected rotation angle.